Yup, the reason the Fatal Frame series is still king as far as I am concerned.
But its not just the walking through walls, its the teleporting, the walking through walls, the vanishing ghosts, the flaming priests, the "Woman in the Box" (Jez this one freaked me the fuck out when I went to save...), the Lords (holy shit the first time you meet one of these), the flashlight going dead, and the list goes on. Fatal Frame did one thing exceptionally well and that was always making your second guess what was coming at you next.
As far as small details mine would have to be the Woman in the Box though, because I didn't expect that one.